i'm not sure if Van Halen counts. Nine Inch Nails was built on changing styles. same with David Bowie and Marilyn Manson.
one that pissed me off was Chimaira. they started off as a pretty decent nu-metal outfit, backwards hats and such, when they did "pass out of existence". then two years later nu-metal was out but the "new wave of american heavy metal" was in with bands like killswitch engage and lamb of god, so Chimaira immediately changes their image and buys some old slayer t-shirts to fit in. pathetic.